Oklahoma’s state superintendent on Thursday directed all public schools to teach the Bible, including the Ten Commandments, in the latest conservative push testing the boundaries between religious instruction and public education.

The superintendent, Ryan Walters, who is a Republican, described the Bible as an “indispensable historical and cultural touchstone” and said it must be taught in certain grade levels.

The move comes a week after Louisiana became the first state to mandate that public schools display the Ten Commandments in every classroom, which was quickly challenged in court. The Oklahoma directive could also be challenged and is likely to provoke the latest tangle over the role of religion in public schools, an issue that has increasingly taken on national prominence.